Перевод Си на Delphi. Что я делаю не так?

const
  CAr: array [1..3] of Integer = (1145, 1247, 1);
implementation
 
{$R *.dfm}
 
{ TForm1 }
 
function TForm1.MainF: Integer;
type
  TMStruct = Record
    Start: Integer;
    Stop: Integer;
    Code: Integer;
end;
var
  _block: TMStruct;
  ret: Boolean;
  br: DWORD;
  Buf: string;
  h: THandle;
  sz, bum: Integer;
begin
  h:= CreateFile('test.exe',GENERIC_WRITE or GENERIC_READ, 0, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if h=0 Then begin Result:=-1; Exit; end;
  sz:=GetFileSize(h, nil);
  if GetLastError=INVALID_FILE_SIZE Then begin Result:=-2; Exit; end;
  //new(PBuf);
  //if(Buf==0) exit(-3);
 
  ret:= ReadFile(h, Buf, sz, br, nil);
  if not(ret) Then begin Result:=-4; Exit; end;
  if br<>sz Then begin Result:=-5; Exit; end;
 
  //Buf[WriteEnable]=0xC0;
 
  bnum:= sizeof(CAr)/sizeof(_block);
 //for(int n=0;n<bnum;n++)
 {
 _block *bl=&CAr[n];
 int start=bl->Start+1;
 int size=bl->Stop - start;
 Buf[bl->Start]=size;
 for(int i=0;i<size;i++){
 BYTE v=Buf[start+i];
 v^=0xFF;
 Buf[start+i]=v;
 }
 
 
end;

ReadFile(h, @Buf[1], sz, br, nil);

function TForm1.MainF: Integer;
type
  TMStruct = Record
    Start: Integer;
    Stop: Integer;
    Code: Integer;
end;
const
  CAr: array [1..3] of Integer = ($479,$4DF,1);
  WriteEnable: Integer =$1FF;
var
  bl: ^TMStruct;
  ret: Boolean;
  br: DWORD;
  Buf, c: ^byte;
  h: THandle;
  sz, v: Byte;
  bnum, st, size, i, n: Integer;
begin
  h:= CreateFile('test.exe',GENERIC_WRITE or GENERIC_READ, 0, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if h=0 Then begin Result:=-1; Exit; end;
  sz:=GetFileSize(h, nil);
  if GetLastError=INVALID_FILE_SIZE Then begin Result:=-2; Exit; end;
  Buf:= nil;
  Buf:= @sz; //Buf=new BYTE[sz]
  if Buf= nil Then begin Result:=-3; Exit; end;
  ret:= ReadFile(h, Buf, sz, br, nil);
  if not(ret) Then begin Result:=-4; Exit; end;
  if br<>sz Then begin Result:=-5; Exit; end;
 
  {Buf[WriteEnable]=0xC0}
  //c:= nil;
  //c:= Buf+WriteEnable
  //c^:= $C0;
 
  {int bnum=sizeof(CAr)/sizeof(_block)}
  //bnum:= sizeof(CAr)/sizeof(TMStruct);
  for n:= 0 to bnum do
    begin
      bl:= @CAr[n];
      st:= bl.Start+1;
      size:= bl.Stop -st;
 
      {Buf[bl->Start]=size}
      //c:= nil;
      //c:= Buf+bl.Start
      //c^:= size;
 
      {BYTE v=Buf[start+i]}
      //c:= nil;
      //c:= Buf+st
      //c^:= size;
      for i:= 1 to size do
        begin
          inc(c);
          v:= Buf^;
          v:= v xor 255;
          c^:= v;
        end;
    end;
end;

bnum:= sizeof(CAr) div sizeof(TMStruct);

{Buf[WriteEnable]=0xC0}
c:= nil;
c:= Pointer(DWORD(Buf)+WriteEnable);
c^:= $C0;
 
{Buf[bl->Start]=size}
c:= nil;
c:= Pointer(DWORD(Buf)+bl.Start);
c^:= size;
 
{BYTE v=Buf[start+i]}
c:= nil;
c:= Pointer(DWORD(Buf)+st);
c^:= size;

High(CAr) - Low(CAr)

function TForm1.MainF: Integer;
type
  TMStruct = Record
    Start: Integer;
    Stop: Integer;
    Code: Integer;
end;
const
  CAr: array [1..3] of Integer = ($479,$4DF,1);
  WriteEnable: Integer =$1FF;
  INVALID_SET_FILE_POINTER = DWORD(-1);
var
  bl: ^TMStruct;
  ret: Boolean;
  br: DWORD;
  Buf: array of Byte;
  h: THandle;
  sz, v: Byte;
  bnum, st, size, i, n: Integer;
begin
 
  h:= CreateFile('test.exe',GENERIC_WRITE or GENERIC_READ, 0, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if h=0 Then begin Result:=-1; Exit; end;
  sz:=GetFileSize(h, nil);
  if GetLastError=INVALID_FILE_SIZE Then begin Result:=-2; Exit; end;
  SetLength(Buf, sz);
  //if Buf= nil Then begin Result:=-3; Exit; end;
  ret:= ReadFile(h, @Buf[0], sz, br, nil);
  if not(ret) Then begin Result:=-4; Exit; end;
  //if GetLastError=ERROR_IO_PENDING Then begin Result:=-2; Exit; end;
  if br<>sz Then begin Result:=-5; Exit; end;
 
  {Buf[WriteEnable]=0xC0}
  Buf[WriteEnable]:=$C0;
 
  bnum:= sizeof(CAr) div sizeof(TMStruct);  //int bnum=sizeof(CAr)/sizeof(_block)
  for n:= 0 to bnum do
    begin
      bl:= @CAr[n];
      st:= bl.Start+1;
      size:= bl.Stop -st;
 
      {Buf[bl->Start]=size}
      Buf[bl.Start]:=size;
 
      for i:= 1 to size do
        begin
          v:=Buf[st+i];
          v:= v xor 255;
          Buf[st+i]:= v;
        end;
    end;
 
  if SetFilePointer(h, 0, nil, FILE_BEGIN)=INVALID_SET_FILE_POINTER Then begin Result:=-6; Exit; end;
  ret:= WriteFile(h,Buf,sz,br,nil);
  if not(ret) Then begin Result:=-7; Exit; end;
  if br<>sz Then begin Result:=-8; Exit; end;
  CloseHandle(h);
end;

  {Buf[WriteEnable]=0xC0}
  Buf[WriteEnable]:=$C0;

uses
    Windows, SysUtils;
 
type
    _block = record
        Start, Stop, Code: Integer;
        end;
 
const
    CAr: array [0 .. 0] of _block = ((Start: $479; Stop: $4DF; Code: 1)); 
    WriteEnable: Integer = $1FF;
 
var
    h: THandle;
    sz: Cardinal;
    Buf: PByteArray;
    br: DWORD;
    ret1: LongBool;
    ret2: Cardinal;
    bnum: Integer;
    n, i: Integer;
    bl: ^_block;
    start, size: Integer;
    v: Byte;
 
begin
    h := CreateFile('test.exe', GENERIC_WRITE or GENERIC_READ, 0, nil,
        OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
    if h = 0 then
        halt(-1);
    sz := GetFileSize(h, nil);
    if sz = INVALID_FILE_SIZE then
        halt(-2);
    Buf := nil;
    GetMem(Buf, sz);
    if Buf = nil then
        halt(-3);
    br := 0;
    ret1 := ReadFile(h, Buf, sz, br, nil);
    if ret1 = false then
        halt(-4);
    if br <> sz then
        halt(-5);
    Buf[WriteEnable] := $C0;
    bnum := High(CAr) - Low(CAr);
    for n := 0 to bnum - 1 do
    begin
        bl := @CAr[n];
        start := bl.Start + 1;
        size := bl.Stop - start;
        Buf[bl.Start] := size;
        for i := 0 to size - 1 do
        begin
            v := Buf[start + i];
            v := v xor $FF;
            Buf[start + i] := v;
        end;
    end;
    ret2 := SetFilePointer(h, 0, nil, FILE_BEGIN);
    if ret2 = INVALID_SET_FILE_POINTER then
        halt(-6);
    ret1 := WriteFile(h, Buf, sz, br, nil);
    if ret1 = false then
        halt(-7);
    if br <> sz then
        halt(-8);
    CloseHandle(h);
    halt(0);
end.